Interlocking plastic building block



FIG. 1 is a perspective view of an interlocking plastic building block showing my new design;

FIG. 2 is a top plan view thereof;

FIG. 3 is a front view thereof;

FIG. 4 is a side view thereof;

FIG. 5 is a bottom view thereof; and,

FIG. 6 is a perspective bottom view thereof.

The sides opposite to those shown in FIGS. 3 and 4 are identical thereto. 

The ornamental design for an interlocking plastic building block, as shown and described. 